4-phenylquinol is a known compound, and a process for its preparation (modified Bamberger's reaction) and isomerization to phenylhydroquinone are disclosed in Chemical Abstracts 1943 2181i.
The use of ceric methylsulfonate as an oxidizing agent for organic compounds dissolved in an aqueous-organic cosolvent system is known and taught in U.S. Pat. No. 4,670,108 to Kreh et al. In this patent the ceric ion is regenerated electrolytically, and the reaction is termed to be an "indirect electrochemical oxidation". The term refers to an oxidation of a compound which proceeds in two steps such that the first step provides a metal ion oxidant (ceric ion) by anodic charge exchange and the second step comprises reacting the metal ion oxidant with a aromatic compound to produce carbonyl containing compound. The indirect electrochemical oxidation of the organic substrate can be conducted in the electrochemical reactor (in-cell) or in a separate reactor (ex-cell).
The oxidation of biphenyl using a solution containing ceric ammonium nitrate to produce 2-phenylbenzoquinone, i.e. ##STR3## is disclosed in U.S. Pat. No. 3,873,580 to Rennie. 2-phenylbenzoquinone can be reduced with hydrogen to produce phenylhydroquinone, i.e. ##STR4##